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MatPlus.Net Forum Competitions Quick Composing TT-236 (h#2) C. 30-12-2019

Quick Composing TT-236 (h#2) C. 30-12-2019

Editorial board of international web project "SuperProblem" (http://superproblem.ru/index-en.html) announces a quick composing thematic tourney for helpmates in two moves.

Awards will be published on the website http://superproblem.ru

View the announcement on the link http://superproblem.ru/htm/announcements/our_tourneys-2019.html#TT-236

Vitaly, how to interpret the word exactly in: "B1 enables (makes possible) EXACTLY the first White's move (W1)".
Does it mean the Exmaple 2 is thematic or not?

Probably it means that B2 or W2 move should NOT be enabled by B1 move.

@ Marjan & all interested

Probably, SOLELY or EXCLUSIVELY would be better.
Seetharaman has understood correctly: it means that B2 or W2 should NOT be enabled by B1 :-)

Example 2 is non-thematic since B1 enables both: W1 and B2.

By the way, W2 should NOT be enabled by W1, too

I'm sorry to continue the nitpicking, but technically in example 2 B1 does not "enable" B2 because it is still illegal before W1. B1 only contributes to B2 becoming possible, the problem is therefore that there are multiple reasons for B2 becoming possible. Maybe a precise formulation would be "The n-th half-move is made possible/legal only through the n-1-th half-move"? So there would have to be some sort of gedankenexperiment where in the initial position you execute the n-1-th half-move and, disregarding other consequences like illegal checks, check whether the n-th half-move has been made possible/legal. If that is not the case, then the problem would be non-thematic, right?

Now imagine the following:
(= 3+3 )

Let's say the (absurd) sequence 1.Qb1 Se4 2.Ba7 Rh3# were a solution. W2 is not possible due to the Be3 standing in the way. This obstacle is removed by B2. B1 makes W1 possible, but it also makes W2 "less possible", and W1 not only makes B2 possible, but also removes the obstacle for W2 that has been produced by B1. Would that be non-thematic as well? (It would be highly interesting, of course, but also almost impossible to compose, I imagine.)

@ Jakob
I'm sorry too since my English is not perfect :-)
But I thought that the word "MEDIATELY" means "after W1" in my comment to example 2, i.e. B1 enables (makes possible) not only W1 but also B2 after W1
Your example is very interesting (dynamic creation of negative effect for W2) but it is non-thematic.

I understand that the use of "impossible (illegal)" means that also simple line opening to enable a move is thematic

(8) Posted by Vitaly Medintsev [Saturday, Nov 30, 2019 10:58]

@ Paz

True, line opening (gate-opening) might be used as thematic feature.
B1 and W1 are thematic moves in the following example:

(= 3+9 )

h#2 2 sols.

1.Rc5 Bxe5 2.O-O-O Rxc5#

1.Rc6 Bd6 2.Rd8 Rxe5#